A neurologic pathway by which non-damaging but high frequency brain impact blunts normal brain function and causes long-term problems with learning and memory has been identified. The finding suggests that tailored drug therapy can be designed and developed to reactivate and normalize cognitive function, say neuroscientists.

The investigators, working with collaborators at the National Institutes of Health, had previously found that infrequent mild head impacts did not have an effect on learning and memory, but in their new study, reported May 10 in Nature Communications, the investigators found that when the frequency of these non-damaging head impacts are increased, the brain adapts and changes how it functions. The investigators have found the molecular pathway responsible for this down-tuning of the brain that can prevent this adaptation from occurring.

This study is the first to offer a detailed molecular analysis of what happens in the brain after highly repetitive and very mild blows to the head, using mice as an animal model, says the study’s senior investigator, Mark Burns, PhD, an associate professor in Georgetown’s Department of Neuroscience and head of the Laboratory for Brain Injury and Dementia.

«Most research in this area has been in mouse models with more severe brain injury, or in human brains with chronic traumatic encephalopathy (CTE),» he says. CTE is a degenerative brain disease found in people with a history of repetitive head impact. «This means that we have been focusing only on how CTE pathology develops. Our goal was to understand how the brain changes in response to the low-level head impacts that many young football players, for example, are regularly experiencing.»

Researchers have found that the average high school and college football player receives 21 head impacts per week, while some specialized players, such as defensive ends, experience twice as many. Behavioral issues believed to come from head impact have been reported in athletes with exposure to repeated head impacts. Issues range from mild learning and memory deficits to behavioral changes that include aggression, impulsivity and sleep disorders.

«These findings represent a message of hope to athletes and their families who worry that a change in behavior and memory means that CTE is in their future,» says Burns.

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